Interference is possible in

A microscope is focussed on a mark on a piece of paper and then a slab of glass of thickness 3cm and refractive index 1.5 is placed over the mark. How should the microscope be moved to get the mark in focus again?

Colours of thin soap bubbles are due to

A telescope has an objective lens of 10cm diameter and is situated at a distance of one kilometre from two objects. Find out the minimum distance between these two objects, which can be resolved by the telescope, when the mean wavelength of light is 5000 Å.

A ray is incident at an angle of incidence i on one surface of a prism of small angle A and emerge normally from opposite surface. If the refractive index of the material of prism is μ, the angle of incidence is nearly equal to :

A planoconvex lens is made of a material of refractive index μ = 1.5. The radius of curvature of curved surface of the lens is 20 cm. If its plane surface is silvered, the focal length of the silvered lens will be :

Which of the following phenomenon is not explained by Huygen's construction of wavefront?

If two mirrors are kept inclined at 60° to each other and a body is placed at the middle, then total number of images formed, is

Light travels through a glass plate of thickness t and refractive index μ. If c is the speed of light in vaccum, the time taken by light to travel this thickness of glass is 

For the given incident ray as shown in figure, the condition of total internal reflection of the ray will be satisfied if the refractive index of block will be